Rodney King told TMZ … he sincerely hopes Trayvon Martin‘s family will eventually get justice … but says Trayvon’s case makes him realize how lucky he was to have his beating captured on tape.

Just days before the 20 year anniversary of the L.A. riots, King was in NYC promoting his new book in which he describes his journey through the violence … from the infamous beating at the hands of LAPD officers … to his public plea for peace.

“It’s not one day that goes by that I don’t think about the incident … I get these headaches … when I [sniff], my sinuses start burning.”

Now, with the Trayvon Martin case stirring up similar emotions as his legal saga … King says the judicial system is a “slow process” …. and adds, “I’m hoping he gets justice for his family … ’cause he’s no longer here, so for his family.”